Frequencies for first 10,000 rows of spec variable in namcs2005 dataset :

  physician |
  specialty |      Freq.     Percent        Cum.
------------+-----------------------------------
          A |         40        0.40        0.40
         CD |         31        0.31        0.71
          D |         70        0.70        1.41
         EM |         28        0.28        1.69
        END |         51        0.51        2.20
         FP |      4,055       40.55       42.75
        FSM |         82        0.82       43.57
         GE |         16        0.16       43.73
         GP |        293        2.93       46.66
         GS |        515        5.15       51.81
         HO |         50        0.50       52.31
         IM |      1,647       16.47       68.78
         MG |          7        0.07       68.85
        MPD |         16        0.16       69.01
        NEP |         34        0.34       69.35
        OBG |         51        0.51       69.86
         OM |         26        0.26       70.12
         ON |         29        0.29       70.41
        OPH |         70        0.70       71.11
        ORS |        105        1.05       72.16
         OS |          8        0.08       72.24
        OTO |         48        0.48       72.72
          P |         22        0.22       72.94
         PD |      2,521       25.21       98.15
        PDC |         13        0.13       98.28
        PDE |         35        0.35       98.63
         PM |         10        0.10       98.73
        PMD |         16        0.16       98.89
         PN |         31        0.31       99.20
        PUD |         11        0.11       99.31
        RHU |         28        0.28       99.59
          U |         33        0.33       99.92
         VS |          8        0.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016